1. Field
Aspects of the present invention generally relate to an image forming apparatus that detects a user and returns the image forming apparatus to a standby state from a sleep state.
2. Description of the Related Art
In a single function peripheral (SFP) such as a printer or the like, or a multi-function peripheral (MFP) including a plurality of these functions, awareness of environmental issues has increased in recent years. These devices are provided with power-saving functions of shifting to a sleep state (power-saving state) while they are not in use, thus reducing their power consumption(s).
These devices perform return-from-sleep operation from a sleep state to a standby state according to whether, for example, they receive print jobs, or a specific time is reached. Further, these devices, in a case where the device is in the sleep state when a user moves in front of a device and operates it, perform a return operation from the sleep state by a power saving button pressed by the user for returning to the standby state from the power saving state.
However, since the return-from-sleep operation will not be performed if the user does not press the power saving button, and the return-from-sleep operation begins only after the button is pressed, the user will be forced to wait in front of the device until the device returns to a usable state (standby state).
A device capable of detecting a human body coming close to a device with a sensor (hereinafter, referred to as a human sensor), and automatically shifting to a standby state from a low power mode or a sleep state is known (see Japanese Patent Application Laid-Open No. 11-202690).
Further, there are some devices that improve energy-saving properties and inhibit erroneous detections by providing two human sensors having different characteristics. This technique is designed by combining two types of sensors, a pyroelectric sensor and a reflective sensor, to perform energy-saving by constantly energizing the pyroelectric sensor with extremely small power consumptions and not energizing the reflective sensor from initial stage. Further, in order to suppress a number of times of returns from sleep caused by erroneously detecting a person simply passing in front of the image forming apparatus, the return-from-sleep operation is executed only when both the pyroelectric sensor and the reflective sensor detect an approach of a human body.
In such a device, when the return-from-sleep operation is started by detecting an approach of a human body using the human sensor, and the user comes in front of the operation unit of the device and operates it, the device has already shifted to the standby state. Consequently, the user can comfortably use the device without virtually any waiting time.
However, conventionally, in an image forming apparatus that returns from the sleep state using the human sensor, in some cases the human sensor may not operate properly due to decrease of a detection range of the human sensor resulting from device failure, or installation environment of the image forming apparatus, etc. Japanese Patent Application Laid-Open No. 11-202690 does not address this situation.
In the event a human sensor is malfunctioning, the human sensor will not be effective. In such a case, even when a user moves into a detection range of the human sensor, the human sensor is unable to detect the user, and thus the return-from-sleep operation is not executed. Therefore, the return-from-sleep operation has to be performed by the user pressing the power-saving button, and convenience of the image forming apparatus equipped with the human sensor will be impaired.
A user who knows that a device is equipped with the human sensor may become aware if the human sensor malfunctions. However, a user who does not know the device is equipped with a human sensor will not know if the human sensor is malfunctioning. Therefore, a delay in repairing the human sensor will occur.